ATEs test signal characteristics of DUTs. For example, an ATE may determine a signal-to-noise (SNR) ratio of a DUT. Problems arise, however, if the noise floor of the ATE is above the noise performance level of the DUT. What this means is that the ATE is noisier than the DUT. The ATE's noise therefore interferes with measurement of the DUT's noise. As a result, the ATE cannot accurately measure noise characteristics of the DUT.